1. Field of the Invention
This application relates generally to a method and apparatus for evaluating fluid behavior as part of a scientific experiment and, more specifically, to a testbed and testing method of evaluating the behavior of a cryogenic liquid in a microgravity environment. The testbed can be a miniaturized (e.g. CubeSat) satellite testbed that can be launched into low-Earth orbit as a secondary payload aboard a rocket or other vehicle capable of leaving Earth's atmosphere, and that carries an experiment for evaluating cryogenic-liquid behavior in microgravity.
2. Description of Related Art
Cryogenic liquids are vital to the continued exploration and exploitation of space, particularly for missions beyond Earth's orbit. For example, liquid cryogens are used as rocket fuel for propulsion of spacecraft. Certain cryogens, e.g. liquid oxygen, are densified forms of atmospheric gases suitable for human respiration that may prove invaluable for storage on long space missions, for example a manned mission to Mars. These cryogens must be stored in tanks carried by the spacecraft for use as-needed, e.g. for thrust, maneuvering, course adjustment or breathing.
The behavior of liquid cryogens in storage tanks within the atmosphere and subject to Earth's gravity has been studied and is well understood. But despite the importance cryogens currently play and will continue to play in orbital and beyond-orbital space missions, there is little data concerning the behavior of liquid cryogens in a micro-gravity environment. Such data would be useful to the design and execution of both orbital and long-range spaceflight missions where liquid cryogens are or will be stored onboard a spacecraft for use during the mission.
A key hurdle to studying the behavior of cryogenic liquids in space is cost. A recent estimate to construct and launch a satellite-based testbed to evaluate cryogenic-liquid behavior was $100 to $200 million. To this point, the associated high cost has stood in the way of this important work. There is accordingly a need for an economical and practical satellite testbed for evaluating cryogenic-liquid behavior in a microgravity environment.